To configure the tolling system for an ever increasing number of vehicles on the roads as efficiently as possible, fully automated road toll systems that have a method of operation based on radio communications between radio beacons (roadside equipment, RSE) and mobile onboard units (OBUs) are being increasingly used.
A radio beacon only has a limited radio coverage area, in which radio communications with the OBUs of the passing vehicles can occur. The size of the radio coverage area and the speed of the vehicle when travelling through this define the time span available for the radio communication. Conversely, specific radio communications, e.g. toll transactions, require a predetermined minimum time for completion, which restricts the vehicle speed until a proper communication with the OBUs is possible.
This problem is intensified further when OBUs are used to save energy, when they are not transmitting by reverting to an energy-saving resting mode, from which they are only “woken up”, i.e. are switched over into the working mode, by a request or prompt signal of the beacon on entry in the radio coverage area of a beacon. The switching over or waking requires additional time, which further cuts into the time span available for the radio communication and thus further reduces the maximum speed of the vehicles that can be processed with the toll system. Known radio communication methods and devices of this type are therefore only suitable for relatively slow vehicles such as heavy goods vehicles (HGV) and fail in the case of fast moving standard passenger cars (SPC).
A known solution for extending such a road toll system for fast moving vehicles lies in erecting an additional radio beacon as “prompting beacon” in front of the radio beacon provided for the radio communication, the “communication beacon”, in the direction of travel. The prompting beacon transmits a prompting signal to the OBU, so that this travels into the radio coverage area of the communication beacon already in work mode. The problem of wake up time is thus overcome. However, the disadvantage of this solution is the substantial cost increase for the user of the road toll system caused by the additional prompting beacons.